Triangular is a tool I developed to design a cover of the Creative Review magazine.

You place points with your mouse and the tool draws connecting lines between the points, if the lines don't overlap any existing lines.

Click + Drag a point to move it.

Shift + Click a point or line to remove it.

The resulting grid is colored using the four color theorem, which states that, given any separation of a plane into contiguous regions, no more than four colors are required to color the regions of the plane so that no two adjacent regions have the same color.